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Comment: Re:In Orbit? (Score 1) 54

by Trapezium Artist (#47627051) Attached to: Rosetta Achieves Orbit Around Comet

Glad to see that you jumped in on this: good description.

Because the comet is so small, the gravity changes a lot with "altitude" from the surface. For a 2-km diameter sphere, say, then the difference in gravity between an altitude of 2-km and 6-km (i.e. between 4 and 8-km from the centre of the sphere) is a factor of 4. On the Earth, it barely changes at all between altitudes of 2 and 4-km, because this is a tiny change relative to the 6400-km radius of the Earth.

So, yes, at 100-km and 50-km, we'll be flying these hyperbolic arcs (slightly bent by the very weak gravity), using thrusters to "turn the corner" at the end of each leg. But at 30-km, we'll be on closed more-or-less circular orbits: I'm pretty sure that it is natural orbit though (and thus fairly long in duration), but not powered.

I do work on the project, albeit not on the flight dynamics side. One of our experts on this, Frank Budnik, did give a talk on this in the science session I moderated yesterday afternoon, starting at 11:28 into the recording of the live stream here:

http://www.esa.int/spaceinvideos/Videos/2014/08/Rosetta_at_comet_First_images_science_results

Comment: Re:FUD filled.... (Score 1) 212

It sounds like this transformer had its center tap grounded and was the path to ground on one side of a ground loop as the geomagnetic field moved under pressure from a CME, inducing a common-mode current in the long-distance power line. A gas pipeline in an area of poor ground conductivity in Russia was also destroyed, it is said, resulting in 500 deaths.

One can protect against this phenomenon by use of common-mode breakers and perhaps even overheat breakers. The system will not stay up but nor will it be destroyed. This is a high-current rather than high-voltage phenomenon and thus the various methods used to dissipate lightning currents might not be effective.

+ - Letter to Congress: Ending U.S. Dependency on Russia for Access to Space 1

Submitted by Bruce Perens
Bruce Perens (3872) writes "I've sent a letter to my district's senators and member of congress this evening, regarding how we should achieve a swifter end to U.S. dependency on the Russians for access to space. Please read my letter, below. If you like it, please join me and send something similar to your own representatives. Find them here and here. — Bruce

Dear Congressperson Lee,

The U.S. is dependent on the Russians for present and future access to space. Only Soyuz can bring astronauts to and from the Space Station. The space vehicles being built by United Launch Alliance are designed around a Russian engine. NASA's own design for a crewed rocket is in its infancy and will not be useful for a decade, if it ever flies.

Mr. Putin has become much too bold because of other nations dependence. The recent loss of Malaysia Air MH17 and all aboard is one consequence.

Ending our dependency on Russia for access to space, sooner than we previously planned, has become critical. SpaceX has announced the crewed version of their Dragon spaceship. They have had multiple successful flights and returns to Earth of the un-crewed Dragon and their Falcon 9 rocket, which are without unfortunate foreign dependencies. SpaceX is pursuing development using private funds. The U.S. should now support and accelerate that development.

SpaceX has, after only a decade of development, demonstrated many advances over existing and planned paths to space. Recently they have twice successfully brought the first stage of their Falcon 9 rocket back to the ocean surface at a speed that would allow safe landing on ground. They have demonstrated many times the safe takeoff, flight to significant altitude, ground landing and re-flight of two similar test rockets. In October they plan the touchdown of their rocket's first stage on a barge at sea, and its recovery and re-use after a full flight to space. Should their plan for a reusable first-stage, second, and crew vehicle be achieved, it could result in a reduction in the cost of access to space to perhaps 1/100 of the current "astronomical" price. This would open a new frontier to economical access in a way not witnessed by our nation since the transcontinental railroad. The U.S. should now support this effort and reap its tremendous economic rewards.

This plan is not without risk, and like all space research there will be failures, delays, and eventually lost life. However, the many successes of SpaceX argue for our increased support now, and the potential of tremendous benefit to our nation and the world.

Please write back to me.

Many Thanks

Bruce Perens"

Comment: Re:Evolution (Score 1) 253

by Bruce Perens (#47485313) Attached to: New Treatment Stops Type II Diabetes

:-)

You make it sound like starving people are getting fat too.

If they are becoming obese, the particular individual has a surplus of caloric intake, if only for this year or month. This is not to say that they have proper nutrition. So I am not at all clear that the fact that there is obesity in the third world is confounding evidence.

Comment: Evolution (Score 1) 253

by Bruce Perens (#47480445) Attached to: New Treatment Stops Type II Diabetes
For most of the existence of mankind and indeed all of mankind's progenitors, having too much food was a rare problem and being hungry all of the time was a fact of life. We are not necessarily well-evolved to handle it. So, no surprise that we eat to repletion and are still hungry. You don't really have any reason to look at it as an illness caused by anything other than too much food.

Comment: Re: If you pay... (Score 2) 15

Martin,

The last time I had a professional video produced, I paid $5000 for a one-minute commercial, and those were rock-bottom prices from hungry people who wanted it for their own portfolio. I doubt I could get that today. $8000 for the entire conference is really volunteer work on Gary's part.

Someone's got to pay for it. One alternative would be to get a corporate sponsor and give them a keynote, which is what so many conferences do, but that would be abandoning our editorial independence. Having Gary fund his own operation through Kickstarter without burdening the conference is what we're doing. We're really lucky we could get that.

Comment: Re:One hell of a slashvertisement! (Score 2) 15

I think TAPR's policy is that the presentations be freely redistributable, but I don't know what they and Gary have discussed. I am one of the speakers and have always made sure that my own talk would be freely redistributable. I wouldn't really want it to be modifiable except for translation and quotes, since it's a work of opinion. Nobody should get the right to modify the video in such a way as to make my opinion seem like it's anything other than what it is.

If you think nobody cares if you're alive, try missing a couple of car payments. -- Earl Wilson

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